Buttermilk Cream Salad Dressing

Four lines and no method, which was normal for a dressing in a book of this vintage. The only real difficulty is the first ingredient.

• What "buttermilk cream" wasIn a dairy that still churned, buttermilk was the liquid left after the butter came, slightly soured and thicker than milk. "Buttermilk cream" most likely means the richer, soured cream associated with it — thicker than milk, thinner than heavy cream — though the recipe does not define the term. The nearest modern stand-ins are crème fraîche thinned with a spoonful of cultured buttermilk, or full-fat buttermilk whisked with an equal amount of heavy cream.
• Cultured buttermilk is not the same thingSupermarket buttermilk is skim or low-fat milk soured with a culture, so it has almost no fat. Used alone here it makes a thin, sharp dressing rather than a creamy one. Add fat back in some form if you want the texture the original assumes.
• MethodWhisk the salt into the vinegar until it dissolves, then beat the vinegar into the cream in a thin stream. Adding acid to cream all at once can curdle it into visible flecks; slowly, it simply thickens.
• CayenneNo quantity is given. "A few grains" is the usual period phrasing for cayenne — roughly a pinch, an eighth of a teaspoon at most. Cayenne here is for warmth at the back of the palate, not heat you can identify.
• VinegarUnqualified vinegar in an American book of this period often meant cider vinegar. White wine vinegar works and is milder; distilled white is harsher than the recipe is likely to intend.
• Yield and servingAbout half a cup, enough to dress cucumbers for four. Salt the sliced cucumbers and drain them twenty minutes first, or the water they throw will thin the dressing on the plate.
• KeepingBest made the day you use it. Acidified cream tends to go on thickening in the refrigerator, so it may pour less freely the following day.